Police said Joshua W. Thayer, 33, an employee at the plant was taken by ambulance to The William W. Backus Hospital in Norwich for treatment of a chemical burn injury as a result of the explosion. He was treated and released. No other injuries were reported.

State and federal emergency crews responded with local crews from throughout the region to the report of the explosion Friday morning.

Police said a box trailer adjacent to the building was badly damaged by acid and the air in the trailer contained gas. Emergency personnel remained on scene and were waiting for a chemical reaction to finish before completing the cleanup and investigation.

The scene was later deemed safe and state police say a preliminary investigation has determined that this appears to be an industrial accident. Troopers assigned to the Fire & Explosion Unit are conducting the investigation.